Fixes a flake where the following can happen:

• A buildstarts at23:34:59.981 but ends at23:35:00.205
• When calculating the deadline of 1 hour we set on the build we get00:35:00.205.
• We pass a tick that adds 61 minutes but it's based off thecreated_at instead of thecompleted_at of the build so we get00:35:59.981 which truncates down to00:35:00 which is less than the deadline.

I've gone ahead and fixed it but we should maybe reconsider whether this test should exist inautobuild since it's really testing that the deadline is set correctly inprovisionerdserver. We can't really refactor this test withdbfake without completely obviating what it's trying to test.

fixes#10359